[M T]

I've seen roughly as many pre-print articles saying "Not so fast" about BCG as those suggesting it may be relevant. 

While we're talking about things that may be protective,
this preprint report talks about the frequency of Vitamin D Insufficiency (VDI) in a small set of COVID patients.
Vitamin D Insufficiency is Prevalent in Severe COVID-19

Twenty COVID-19 patients with serum 25OHD levels were identified; 65.0% required ICU admission.The VDI prevalence in ICU patients was 84.6%, vs. 57.1% in floor patients. Strikingly, 100% of ICU patients less than 75 years old had VDI.

Off-topic here, but not worth its own thread,
Reconstructed diagnostic sensitivity and specificity of the RT-PCR test for COVID-19
calculates the China RT-PCR test (only; not applicable to any other RT-PCR test) sensitivity and specificity:
"The sensitivity of the RT-PCR diagnostic test was estimated to be 0.777 (95% CI: 0.715, 0.849), while the specificity was 0.988 (95% CI: 0.933, 1.000)."

[M T]

I've seen roughly as many pre-print articles saying "Not so fast" about BCG as those suggesting it may be relevant. 

While we're talking about things that may be protective,
this preprint report talks about the frequency of Vitamin D Insufficiency (VDI) in a small set of COVID patients.
Vitamin D Insufficiency is Prevalent in Severe COVID-19

Twenty COVID-19 patients with serum 25OHD levels were identified; 65.0% required ICU admission.The VDI prevalence in ICU patients was 84.6%, vs. 57.1% in floor patients. Strikingly, 100% of ICU patients less than 75 years old had VDI.

Off-topic here, but not worth its own thread,
Reconstructed diagnostic sensitivity and specificity of the RT-PCR test for COVID-19
calculates the China RT-PCR test (only; not applicable to any other RT-PCR test) sensitivity and specificity:
"The sensitivity of the RT-PCR diagnostic test was estimated to be 0.777 (95% CI: 0.715, 0.849), while the specificity was 0.988 (95% CI: 0.933, 1.000)."